ZoneMinder uses shared memory to speed up communication between modules. To identify the right area to use shared memory keys are used. This option controls what the base key is, each monitor will have it's Id or'ed with this to get the actual key used. You will not normally need to change this value unless it clashes with another instance of ZoneMinder on the same machine. Only the first four hex digits are used, the lower four will be masked out and ignored.